This invention relates generally to Global navigation satellite system (GNSS) direct sequence spread spectrum receivers. Examples of GNSS receivers include Global Positioning System (GPS) receivers, Galileo receivers (the European equivalent of GPS), GLONASS receivers (the Russian equivalent of GPS), and Space Based Augmentation System (SBAS) receivers. As an example, the GPS (which predates Galileo, GLONASS, and SBAS) operates by broadcasting direct sequence spread spectrum timing signals on L1 (1575.42 MHz) and L2 (1227.6 MHz) carrier frequencies from a constellation of greater than 24 satellites in a half geo-synchronous orbit. These signals, when properly processed by a GNSS receiver, permit determination of position and velocity.
With existing receivers, the measurements of satellite information are usually taken at periodic time epochs, each epoch denoted as a TIC. TIC is an internally generated signal produced by each multi-channel correlator within the receiver. The correlator is the portion of the receiver that performs the high-speed digital processing necessary to track geo-location satellites. However, as each receiver operates independently, each receiver acquires its data asynchronously. Asynchronous acquisition of data leads to timing discrepancies between correlators. Therefore, it is desired to have a method and an apparatus for synchronizing the precise timing of measurements across multiple correlators and receivers. Furthermore, it is desired that a receiver and correlator be user configurable as desired to facilitate the synchronization.